This invention relates to a high temperature aluminum electrolytic capacitor, and more particularly to such a capacitor which utilizes an electrolyte comprising a mixed solvent system of N-methylpyrrolidinone and ethylene glycol plus a mixed solute system of diethylammonium fumarate to provide a capacitor capable of operation at 125.degree. C.
Prior art electrolytes that are based predominantly on ethylene glycol have proven extremely useful at temperatures up to about 95.degree. C., more generally 85.degree. C. For temperatures above 85.degree. C., the solvent of choice has been dimethylformamide (DMF) usually. Some electrolytes now in use at 125.degree. C. contain solvent mixtures of ethylene glycol and DMF.
However the interest in the replacement of DMF has become more popular due to: (1) potential toxicity problems, which require stringent handling procedures; (2) difficulty in disposal of capacitors containing the solvent; and (3) low flash point, which creates a flammability problem.
It is an object of this invention to provide aluminum electrolytic capacitors capable of operating at 125.degree. C. with the above-identified problems minimized or eliminated. Another object is to provide a solution to those prior art problems which involve choices in electrolyte composition and material selection.